1. Field of the Invention
The present relates to microwave switches, and more particularly to an integrated pad switch that switches on a planar transmission media over the frequency range from DC to over 40 GHz.
2. Description of the Prior Art
Current switches used in microwave applications are of the suspended contact coaxial type, coaxial turret type, or of the slab-line type shown in FIGS. 1 and 2. These slab-line switches consist of a contact 10 which is essentially cantilever-mounted in a cavity 12. The end of the contact is physically moved to make contact between either an integrated circuit hybrid 14 or a metal contact 16, to select between a resistive network and a through path, for example. the electric field 18 exists between the sides of the contact and the walls of the cavity. Thus, the clearance between such walls and the contact edges is critical, and due to tolerance buildups this type of switch has a practical upper frequency limit of approximately 26 GHz.
The suspended contact coaxial type switches are generally solenoid-operated, push-pull mechanisms which move a spring-loaded contact to make or break a circuit. These switches have an upper frequency limit due to SWR and return loss, and are restricted by the practical limit of the cavity dimensions.
The coaxial turret type switches have a cylindrical attenuator between two coaxial inputs. The attenuator rotates to switch circuits between the two coaxial inputs. This switch has ground path problems.
What is desired is a microwave switch which does not have the frequency limitations of the prior swtiches, and can operate at 40 GHz or better.